Revert "Remove vendored libjuju"

This reverts commit 9d18c22a0dc9e295adda50601fc5e2f45d2c9b8a.

Change-Id: I7dbf291ccd750c5f836ff80c642be492434ab3ac
Signed-off-by: Adam Israel <adam.israel@canonical.com>
diff --git a/modules/libjuju/tests/bundle/invalid.yaml b/modules/libjuju/tests/bundle/invalid.yaml
new file mode 100644
index 0000000..2e51c1e
--- /dev/null
+++ b/modules/libjuju/tests/bundle/invalid.yaml
@@ -0,0 +1,7 @@
+applications:
+  myapp:
+    charm: cs:xenial/ubuntu-0
+    num_units: 1
+    to:
+      - 0
+      - 0